1. Field of the Invention
The present invention relates to an image processing apparatus.
Priority is claimed on Japanese Patent Application No. 2013-070597, filed Mar. 28, 2013, the content of which is incorporated herein by reference.
2. Description of the Related Art
In recent years, the reduction of a processing time necessary for image processing, for example, has been required to cope with high-definition moving images such as full high-vision moving images in an imaging apparatus such as a digital camera or a digital video camera. As one method according to this requirement, for example, Japanese Unexamined Patent Application, First Publication No. 2010-278532 (hereinafter referred to as Patent Literature 1) discloses a method of dividing an image of one frame into a plurality of blocks and performing imaging processing on each division block (see FIGS. 16A and 16B).
Although a flow of image data to be processed within each division block is continuous when the image of one frame is divided into a plurality of blocks as illustrated in FIG. 16A, a flow of image data between different blocks is not continuous (see FIG. 16B). Thus, when a spatial filtering process is performed in image processing on each block, a so-called “overlap width area,” which is an overlap area of image data, is necessary. Likewise, the image processing apparatus also acquires image data of the overlap width area in addition to image data of a block on which the image processing is performed, thereby performing the image processing in a status in which the image data of the block and the image data of the overlap width area are combined.
In the image processing apparatus, a time taken to acquire the image data of the overlap width area is a factor that interferes with the reduction of a processing time. In technology disclosed in Patent Literature 1, by providing an overlap width saving buffer which saves image data of the overlap width area within the image processing apparatus, the time taken to acquire the image data of the overlap width area for use in the image processing is shortened and the improvement of processing capability for an image is implemented.
In addition, the imaging apparatus is equipped with a so-called live view function of displaying a moving image for viewing a subject to be photographed on a display device mounted on the imaging apparatus. In the live view function, pixel signals of frames are continuously acquired from an image sensor according to live view photography, and the image processing apparatus generates an image (hereinafter referred to as a live view image) of each frame to be displayed on the display device and sequentially displays a live view image of each frame.
In this imaging apparatus, it is also possible to capture a still image while the live view image of each frame is displayed on the display device by the live view function. At this time, the image sensor provided in the imaging apparatus performs switching from the live view photography to still image photography for acquiring a pixel signal of a still image at the timing at which the still image is captured. Then, after the still image has been generated from the pixel signal acquired according to the still image photography, the image processing apparatus performs switching to the live view photography again.
Thus, during a period in which the image sensor performs the still image photography and a period in which the image processing apparatus performs image processing to generate a still image in the imaging apparatus of the related art, it is difficult to perform the live view photography and the imaging apparatus of the related art is in a freeze status in which the live view image displayed on the display device is fixed to the same image or a blackout status in which no live view image is displayed and a black display is made. This is because it is difficult for the image sensor to perform the live view photography during a period in which the still image photography is performed and it is difficult for the image processing apparatus to perform image processing for generating a live view image during a period in which image processing is performed to generate a still image.
In the imaging apparatus, it is desirable to restore (resume) a display of a live view image at an early timing in order to prevent a so-called photo opportunity, which is the timing at which the next still image is captured, from being missed. Patent Literature 1 discloses a configuration in which a plurality of image processing apparatuses are provided within the imaging apparatus and respective image processing sections perform different image processing operations. In the configuration disclosed in Patent Literature 1, it is possible to promptly restore a display of the display device from the freeze status or the blackout status by simultaneously performing image processing for generating a live view image and image processing for generating a still image in parallel in different image processing apparatuses.
Japanese Unexamined Patent Application, First Publication No. 2006-311347 (hereinafter referred to as Patent Literature 2) discloses a method of dividing image processing for generating a still image and performing still image processing of each division during a period in which image processing for generating a live view image is not performed. In technology disclosed in Patent Literature 2, by dividing the still image processing and the image process for generating the live view image according to time division, it is possible to promptly restore a display of the display device from the freeze status or the blackout status even in one image processing apparatus.